There are two major continuing directions of activity. The first direction is the investigation of (local) hospital blood bank problems. The second is the design and analysis of models for regional blood banks. HOSPITAL BLOOD BANK PROBLEMS: Analysis of the supply-demand problems associated with the highly random usage and short lifetime of platelets and other blood components. In this problem, packed red cells are treated as a byproduct. Hence we have a multi-product inventory problem arising from a single input (namely, fresh whole blood) and the optimal policies for deriving, using and storing these products will be obtained. Cost studies are underway to ascertain the processing costs associated with drawing, storing, crossmatching and transfusing blood derivatives. REGIONAL BLOOD BANK PROBLEMS: A mathematical model and a computer simulation model have been developed to analyze the optimal ordering, storing, and shipping from central blood banks (CBB's)to hospital blood banks (HBB's) and transshipment of blood among HBB'S. The models for locating and determining the regional and satellite sizes have also been developed and most of the features have been computer coded. Some data have been gathered at a CBB for application of the results of this study. Some features which must still be added to the computer codes are cost functions for information processing, administration and donor recruitment as a function of system size. In addition we must build submodels for donor recruiting and scheduling. It is anticipated that the data from the CBB will aid in this work. Studies will be conducted concerning a multi-region network model which will analyze the question of interaction among different regional networks. For this problem, new macro-level models still need to be constructed. Work on overall economies and diseconomies of scale due to regionalization has been started.